The invention relates to routing and classification of data packets in a data communications networks. Routing is divided into two different categories that are applicable to different applications. In dynamic routing the routes change according to the changes in the network. In static routing the routing decision and the network do not change or the changes are not that frequent. When the network is reasonably static, static routing might be beneficial. A common nominator for both routing schemes is that they are based on routing tables. When a switch or router receives a data packet, it makes the routing decision based on the routing data in the routing table. This causes large routing tables that require memory and processing resources.
There are several different publications disclosing enhancements to static routing. For example, U.S. Pat. No. 6,215,765 discloses a method for establishing a switched virtual circuit in a digital network having network nodes with static routing tables. When a node is unable to forward over primary route and the secondary route is the same from where the data packets have arrived, the packet are attempted to reroute dynamically.
EP404339 discloses a further example wherein a packet routing apparatus allows numerous packets to be routed simultaneously through a mesh connected network. For each received packet the router generates a routing mask representing the output links that may be used to route the packet towards it destination. The routing mask includes a broadcast bit. If the broadcast bit is on, the packet must be simultaneously routed to all of the output links specified by the routing mask. If the broadcast bit is off, the packet may be routed on any single one of the links specified by the routing mask. U.S. Pat. No. 6,778,539 discloses using only a part of the destination address with the routing table. Thus this solution concerns an optimization of existing background art using routing tables.
The prior art solutions for static routing require full-size or longest prefix-based aggregated routing tables or broadcasting. This is inefficient as the preformed routing decisions are static by nature. The standard approach is based on the full implementation of the route lookup procedure that performs a search for the longest prefix match in the routing table for each packet. It increases implementation complexity of the network nodes and switches, requires high speed memory for storing routing tables and results in additional processing delay and energy consumption for each transmitted packet. Thus, there is a need for solution that simplifies the implementation and solves the other drawbacks of the prior art.